Distinct and combined impacts of future climate and land use change on the flow of River Rwizi in Uganda, East Africa

Abstract

Although many studies have assessed the singular impacts of future land use and climate change on river hydrology, few studies have investigated the distinct and combined impacts of land use and climate change on river flows particularly in developing countries faced with a challenge of limited data. This study addressed the aforementioned gap and applied the Soil and Water Assessment Tool and an ensemble of six CORDEX Regional Climate Models under the moderate (RCP4.5) and high (RCP8.5) emission scenarios in the River Rwizi catchment area in western Uganda for the period 2021–2050. The isolated impacts of land use change and the combined impacts showed an increase in future total annual river flows. However, the isolated impacts of climate change showed a reduction in future total annual flow. The influence of land use changes on total annual runoff was more dominant than that of climate change. The results show that climate change is the dominant factor impacting future high-flow quantiles while future annual flow and extreme low-flow variations were attributed mainly to land use changes. These findings point to the need to plan and implement prudent land use and water resource management practices to mitigate associated risks.